They are the only visible trace of a souterrain, an underground stone-lined passage or chamber built in early medieval Ireland, typically for storage or as a place of refuge. What makes this particular example quietly melancholy is not what survives but what was deliberately removed: the souterrain was filled in around 1967 when the hillside was cleared of trees and the land reclaimed for rough pasture.

The site at Boolahallagh sits on steeply sloping upland terrain, and its location was known locally, passed on by the occupants of nearby Bonnard House. That kind of informal, place-based memory is often the only thread connecting modern observers to features that have otherwise vanished from the landscape entirely. Once the souterrain was backfilled during the land reclamation work of the late 1960s, the structure itself ceased to exist in any meaningful archaeological sense. What remained were depressions in the ground, suggestive of the shape of something beneath but offering no access and no real legibility to a passing eye.